This proposal seeks renewal of R01 AG006537 for years 20-24 to provide continuing support for our work in the integrative physiology of human aging. The proposed research will determine if caloric restriction- induced weight loss improves vascular endothelium-dependent dilation (EDD), a clinically important marker of endothelial function and atherosclerotic disease risk, in overweight and mildly obese middle-aged and older adults. We also will determine the role of reduced inflammation, oxidative stress and visceral adiposity in mediating these beneficial effects of weight loss on EDD. Our integrative working hypothesis is that: --EDD will be improved following weight-loss -these improvements will be associated with reduced systemic inflammation, a reduced inflammatory vascular endothelial phenotype, and reduced levels of nuclear factor kappa B (NFKB), a key pro- inflammatory transcription factor -the reduced inflammation-related improvements in EDD will be associated with decreased oxidative stress mediated suppression of EDD -these integrative physiological adaptations to weight loss will be more closely related to reductions in abdominal visceral adiposity than to decreases in total or abdominal subcutaneous fat. To test this hypothesis we will conduct a 12-week weight loss intervention (randomized attention control design). The tonic influence of inflammation on EDD will be determined before and after the intervention period using short-term blockade of NFKB with orally administered Salsalate. Intravenous infusion of ascorbic acid, a potent antioxidant, will be used to determine the effects of oxidative stress on EDD. Key outcomes will include brachial artery flow-mediated dilation (i.e., EDD);cytokines (plasma levels;whole- blood cell production and protein/mRNA gene expression);blood cell NFKB protein/mRNA gene expression;vascular endothelial expression of inflammation- and oxidant-related proteins;and dual x-ray absorptiometry (total fat)- and computed tomography (abdominal visceral and subcutaneous fat)-measured adiposity. The proposed study should provide the first insight into the role of reduced inflammation, oxidative stress and visceral adiposity in weight loss-mediated improvements in EDD in overweight/obese older adults.